SSD speed in Mac Pro 1,1

[seoulcomp]

You can add either a SATA 6 Gbps PCIe card or a native PCIe SSD. However, a PCIe SSD has to use the AHCI protocol (not NVMe!) to work in the 1,1, and there are very few AHCI PCIe SSDs. I have compiled a list of these elusive SSDs here.


PCIe 1.0 is ≈250 MB/s per lane, minus overhead. If you get a two-lane PCIe SATA 6 Gbps card (don't get a single-lane one, that isn't worth it in the 1,1), you can expect speeds in the 400≈450 MB/s range. The 1,1's internal SATA bus is 300 MB/s (3 Gbps) minus overhead, which usually results in 250≈270 MB/s.

The fastest option, by far, is to get an AHCI PCIe SSD that uses four lanes. Using one of these, you can expect speeds in the 700≈800 MB/s range. And it will be bootable as well.


As said above, the speed you can get depends on the number of PCIe lanes your controller uses.

What do you mean by "2 lanes". Does it have something to do with 16X, 8X, 2X, and 1X? if so, what are those speeds. And I thought the PCI bus was already handicapped on the 1,1, being the original slower variety of PCIe, 1.0?

 

[Amethyst1]

What do you mean by "2 lanes". Does it have something to do with 16X, 8X, 2X, and 1X? if so, what are those speeds.

A PCIe slot can have up to 16 lanes. For PCIe 1.0, each lane is 250 MB/s max (theoretically, i.e. without taking overhead into account).

So, depending on how many lanes a PCIe card uses, the maximum bandwidth it can get in a 1,1 is (theoretically, i.e. without taking overhead into account):

1 lane: 250 MB/s
2 lanes: 500 MB/s
4 lanes: 1000 MB/s
8 lanes: 2000 MB/s
16 lanes: 4000 MB/s

Most (all?) PCIe 6Gbps SATA cards use either one lane or two lanes.

 

[seoulcomp]

You can add either a SATA 6 Gbps PCIe card or a native PCIe SSD.

However, a native PCIe SSD has to use the AHCI protocol (not NVMe!) to work in the 1,1, and there are very few AHCI PCIe SSDs. I have compiled a list of these elusive SSDs here.


PCIe 1.0 is ≈250 MB/s per lane, minus overhead. With overhead, I’d say it’s around 200 MB/s per lane.

If you get a two-lane PCIe SATA 6 Gbps card (don't get a single-lane one — that isn't worth it in the 1,1), you can expect speeds in the 350≈400 MB/s range. The 1,1's internal SATA bus is 300 MB/s (3 Gbps) minus overhead, which usually results in 250≈270 MB/s.

But the fastest option, by far, is to get an AHCI PCIe SSD that uses four lanes. With one of these, you can expect speeds in the 700≈800 MB/s range. And it will be bootable as well.


No. The maximum speed you can get depends on the number of PCIe lanes your controller uses.

But what about 1,1 that has been hacked up to El Capitan? Can that support NVMe PCIe cards (and be bootable)?

 

[seoulcomp]

ah so like a PCIe card that takes SSUAX or SSUBX will work, right? And one cannot just get a third party adapter, for NVMe you have to use like one of those other kind you list, correct?

 

[Amethyst1]

ah so like a PCIe card that takes SSUAX or SSUBX will work, right?

Yup.

And one cannot just get a third party adapter, for NVMe you have to use like one of those other kind you list, correct?

Non-Apple AHCI and NVMe m.2 SSDs use the same connector so you can use any third-party m.2-to-PCIe adapter.

Apple’s SDNEP, SRIUP, SSUAX and SSUBX SSDs and the Transcend JetDrive 820/825 use a custom connector so you need a custom adapter.

 

[seoulcomp]

Right, but NVMe with an adapter will not work on a 1,1 regardless, even if using El Capitan?

 

[Amethyst1]

But what about 1,1 that has been hacked up to El Capitan? Can that support NVMe PCIe cards (and be bootable)?

El Capitan doesn’t recognise third-party NVMe SSDs, only Apple’s.
The 1,1 doesn’t boot from NVMe SSDs.

 

[seoulcomp]

thanks

 

[seoulcomp]

El Capitan doesn’t recognise third-party NVMe SSDs, only Apple’s.
The 1,1 doesn’t boot from NVMe SSDs.

And the AHCI can boot from the option key at started? I heard that you still must choose startup disk from another internal disk first, in order to boot from PCI, or is that not true?